1. Field of the Invention
The present invention is directed to a regulator for regulating the flow of ink from an ink source to a print head in a printer; and, more particularly, to a regulator that is relatively independent upon the inlet pressure, such that the functionality of the regulator is relatively independent of the inlet pressure of the ink source.
2. Background of the Invention
The flow of fluids through predetermined conduits has been generally been accomplished using a valve and/or a pressure source. More specifically, valves come in various shapes and sizes and include as a subset, check valves. These valves prevent the reversal of fluid flow from the direction the fluid passed by the valve. A limitation of check valves is that the volumetric flow of the fluid past the valve is controlled by the inlet side fluid pressure. If the inlet pressure is greater than the outlet pressure, the valve will open and fluid will pass by the valve; if not, the inlet fluid will be relatively stagnant and the valve will not open.
Inkjet printers must take ink from an ink source and direct the ink to the print head where the ink is selectively deposited onto a substrate to form dots comprising an image discernible by the human eye. Two general types of systems have been developed for providing the pressure source to facilitate movement of the ink from the ink source to the print head. These generally include gravitational flow system and pumping systems. Pumping systems as the title would imply create an artificial pressure differential between the ink source and the print head to pump the fluid from the ink source to the print head. Generally, these pumping systems have many moving parts and need complex flow control system operatively coupled thereto. Gravitational flow avoids many of these moving parts and complex systems.
Gravitational fluid flow is the most common way of delivering ink from an ink reservoir to a print head for eventual deposition onto a substrate, especially when the print head includes a carrier for the ink source. However, this gravitational flow may cause a problem in that excess ink is allowed to enter the print head and accumulate, being thereafter released or deposited onto an unintended substrate or onto one or more components of the inkjet printer. Thus, the issue of selective control of ink flow from a gravitational source has also relied upon the use of valves. As discussed above, a check valve has not unitarily been able to solve the problems of regulating ink flow, at least in part because the inlet pressure varies with atmospheric pressure, and when the valve is submerged, the pressure exerted by the fluid itself.
U.S. Pat. No. 6,422,693, entitled xe2x80x9cInk Interconnect Between Print Cartridge and Carriagexe2x80x9d, assigned to Hewlett-Packard Company, describes an internal regulator for a print cartridge that regulates the pressure of the ink chamber within the print cartridge. The regulator design includes a plurality of moving parts having many complex features. Thus, there is a need for a regulator to regulate the flow of ink from an ink source to a print head that includes fewer moving parts, that is relatively easy to manufacture and assemble, and that does not necessitate direct coupling to the atmosphere to properly function.
The invention is directed to a mechanical device providing control over the flow of a fluid from a fluid source to at least a point of accumulation. More specifically, the invention is directed to an ink flow regulator that selectively allows fluid communication between the ink source and the print head so as to supply the print head with ink, while substantially inhibiting the free flow through of print head. The invention comprises a pressurized chamber, generally exhibiting negative gauge pressure therewithin, having an ink flow inlet and an ink flow outlet. A seal is biased against the ink inlet to allow selective fluid communication between the interior of the pressurized chamber and an ink source. A flexible wall, acting as a diaphragm, is integrated with a chamber wall to selectively expand outwardly from and contract inwardly towards the interior of the chamber depending upon the relative pressure differential across the flexible wall. The pressure differential depends upon the pressure of the interior of the chamber verses the pressure on the outside of the flexible wall.
As the flexible wall contracts inwardly towards the interior of the chamber, it actuates a lever. The lever includes a sealing arm and an opposing flexible arm, and pivots on a fulcrum. The sealing arm includes the seal biased against the ink inlet, while the flexible arm is angled with respect to the sealing arm and includes a spoon-shaped aspect contacting the flexible wall. As the flexible wall continues contracting inward, the flexible arm flexes without pivoting the lever until the force of the wall against the flexible arm is sufficient to overcome the bias biasing the sealing arm against the inlet. When the force against the lever is sufficient to overcome the bias, the lever pivots about the fulcrum to release the seal at the ink inlet, thereby allowing ink to flow into the chamber until the pressure differential is reduced such that the bias again overcomes the reduced push created by the inward contraction of the flexible wall.
It is noted that the invention is not a check valve, as the operation of the regulator is independent from the inlet pressure. In other words, a check valve is dependent upon the inlet pressure, whereas this system of the present invention provides a relatively small inlet cross sectional area in relation to the size and relative forces action upon the regulator system that effectively negates any variance in inlet pressure. Thus, increasing the inlet pressure does not affect the operation of the regulator.
It is important for the regulator of the present invention to be compact and take up relatively little volume. In furtherance of these size considerations, the present invention includes an ink inlet aligned with an ink outlet to reduce the overall length. Additionally, the regulator provides the ink outlet and the ink inlet on one side of the lever fulcrum and having the flexible film wall that actuates the lever on the opposite side of the lever fulcrum to reduce the height and width of the regulator.
It is also important for the regulator of the present invention to be as reliable and inexpensive as possible. Further, it is preferable that the lever be able to pivot in a repeatable manner, thus lowering the frictional force losses is an important aspect of the present invention. Still further, it is preferable that the lever does not stick during its pivot and create a spike in negative pressure affecting the functionality of the regulator. In furtherance of these advantages, the invention incorporates materials having properties consistent with the objects and considerations of the present invention to reduce friction where appropriate.
It is a first aspect of the present invention to provide a regulator adapted to regulate the throughput of an ink between an ink source and a print head. The regulator including: (a) a pressurized chamber including an ink inlet adapted to provide fluid communication with an ink source, an ink outlet adapted to provide fluid communication with a print head, and at least one exterior flexible wall having an inner surface facing an interior of the pressurized chamber; and (b) a lever pivotable on a fulcrum including a first arm extending approximate a portion of the exterior flexible wall and an opposing arm operatively coupled to a seal, the seal closing the ink inlet when the lever is in a first position and to opening the ink inlet to allow fluid communication between the ink inlet and the pressurized chamber when the lever is pivoted to a second position, the lever being biased to the first position; where a higher pressure differential across the exterior flexible wall causes the exterior flexible wall to apply force against the first arm, overcoming the bias, to thereby pivot the lever to the second position, opening the ink inlet; where a lower pressure differential across the exterior flexible wall causes the force applied by the exterior flexible wall against the first arm to weaken, succumbing to the bias, which pivots the lever back to the first position, closing the ink inlet; where a pressure change from the lower pressure differential to the higher pressure differential across the exterior flexible wall causes the force applied by the exterior flexible wall to increase without overcoming the bias; and where the ink inlet and the ink outlet are positioned on the same side of the fulcrum as the opposing arm of the lever.
In a more detailed embodiment of the first aspect, the ink inlet and ink outlet are located on opposing faces (i.e., the top and bottom) of the pressurized chamber. In another more detailed embodiment, the ink inlet and the ink outlet are substantially axially aligned with each other. In yet another more detailed embodiment, the ink inlet and the ink outlet are located on adjacent faces of the pressurized chamber. In a further detailed embodiment, the exterior flexible wall comprises a polymer film. In still a further more detailed embodiment, the fulcrum is between the ink inlet and the flexible wall. In yet a further more detailed embodiment, the ink inlet is in fluid communication with at least one of an ink conduit containing ink or an ink reservoir containing ink.
It is a second aspect of the present invention to provide a method of reducing the size of an ink flow regulator in fluid communication between an ink source and a print head nozzle. The method includes the steps of: (a) positioning an ink inlet of an ink flow regulator and an ink outlet of the ink flow regulator in a first section of the ink flow regulator, and (b) orienting a pivotable lever, having a first leg coupled to an inlet closure of the regulator and a second leg operatively coupled to an actuating wall of the regulator such that a fulcrum of the pivotable lever separates the first section from a second section of the ink flow regulator, wherein the first section and the second section are in fluid communication with one another. In a more detailed embodiment of the second aspect, the ink inlet and the ink outlet are oriented to oppose one another.
It is a third aspect of the present invention to provide a regulator adapted to regulate the throughput of an ink between an ink source and a print head. The regulator including: (a) a pressurized chamber including an ink inlet adapted to provide fluid communication with an ink source, an ink outlet adapted to provide fluid communication with a print head, a bearing seat, and at least one exterior flexible wall having an inner surface facing an interior of the pressurized chamber, and (b) a lever including a first arm extending along a portion of the exterior flexible wall, an opposing arm, and a fulcrum bearing adapted to be received within the bearing seat of the pressurized chamber, the opposing arm operatively coupled to a seal to close the ink inlet when the lever is in a first position and open the ink inlet allowing fluid communication between the ink inlet and the pressurized chamber when the lever is pivoted to a second position, the lever being biased to the first position; where a higher pressure differential across the exterior flexible wall causes the exterior flexible wall to apply force against the first arm contacting the exterior flexible wall, overcoming the bias, to thereby pivot the lever to the second position, opening the ink inlet; where a lower pressure differential across the exterior flexible wall causes the force applied by the exterior flexible wall against the first arm contacting the exterior flexible wall to weaken, succumbing to the bias, which pivots the lever back to the first position, closing the ink inlet; and where a pressure change from the lower pressure differential to the higher pressure differential across the exterior flexible wall causes the force applied by the exterior flexible wall to increase without overcoming the bias.
In a more detailed embodiment of the third aspect, the bearing has an actuate shaped surface interfacing with a planar bearing seat surface. In a farther detailed embodiment, the lever is pivoted about a fulcrum adjacent to the ink inlet. In yet a further detailed embodiment, the bearing comprises polyethylene. In a more detailed embodiment, the bearing seat comprises acetyl.
It is a fourth aspect of the present invention to provide a method of regulating the flow of ink between an ink source and a print head nozzle. The method including the steps of: (a) positioning an ink flow regulator adapted to regulate the throughput of an ink between an ink source and a print head nozzle, the regulator including: (i) a pressurized chamber including an ink inlet providing fluid communication with the ink source, an ink outlet providing fluid communication with a print head nozzle, and at least one flexible wall having an inner surface facing an interior of the pressurized chamber; and (ii) a lever including a first arm extending in proximity to a portion of the flexible wall and an opposing arm operatively coupled to a biased valve selectively restricting fluid communication between the ink source and the print head nozzle; wherein ink enters the ink inlet and leaves the ink outlet in a unitary direction; (b) actuating the flexible wall in response to a pressure differential across the flexible wall, wherein an interior surface of the flexible wall is in fluid communication with ink within the pressurized chamber and an exterior surface of the flexible wall is in fluid communication with a fluid; (c) pivoting the lever in response to the actuation of the flexible film, so as to overcome the bias and open the valve in a first pivoting direction, and succumbing to the bias and close the valve in a second pivoting direction, opposite the first pivoting direction; and (d) opening and closing the valve in response to the pivoting of the lever.
In a more detailed embodiment of the fourth aspect, the pivoting step includes providing a bearing and bearing seat that interact to provide free pivoting of the lever about a fulcrum. In another more detailed embodiment, the bearing includes polyethylene. In yet another more detailed embodiment, the bearing seat includes acetyl. In a further more detailed embodiment, the bearing has an actuate shaped surface interfacing with a planar bearing seat surface. In still a further more detailed embodiment, the fulcrum is adjacent to the ink inlet.